US3057393A - Fabrication of blade blanks - Google Patents

Description

Oct. 9, 1962 D. J. CLARKE 3,957,393

FABRICATION OF BLADE BLANKS Filed June 3 1957 3 Sheets-Sheet 1 DANIEL J. CLARKE MMMW ATTORNEYS Oct. 9, 1962 D. J. CLARKE FABRICATION OF BLADE BLANKS 3 Sheets$heet 3 Filed June 5. 1957 INVENTOR.

DANIEL J. CLARKE ATTORNEYS 3,057,393 Patented Oct. 9, 1962 Free 3,057,393 FABRICATION F BLADE BLANKS Daniel J. Clarke, Bay City, Mich assignor to The Stalker Corporation, a corporation of Michigan Filed June 3, 1957, Ser. No. 663,251 6 Claims. (Cl. 153-33) This invention relates to an apparatus and method for forming blades for compressors, turbines and the like, and more particularly to an apparatus and method for folding preformed sheet metal blade blanks about the leading edge of the nose portion to place the trailing edges of the blank into close proximity for joining.

Another object of this invention is to provide a method and apparatus for folding preformed sheet metal blade blanks about a supporting mandrel through the application of comparatively large side forces exerted against the outer portion of the supporting mandrel which prevent excessive mandrel wear While bringing the trailing edges into adjoining relationship.

A primary object of this invention is to to provide an apparatus for folding a preformed blade blank about its leading edge while preserving its precisely formed contours.

Another object of this invention is to provide a method and apparatus for reforming the outer, supporting edge of such a mandrel.

Other objects and advantages of this invention will be apparent from the following description, the accompanying drawings and the appended claims.

In the drawings:

FIG. 1 is a perspective view showing an apparatus ac cording to the present invention with a preformed blade blank supported on the mandrel;

FIG. 2 is a perspective view of a shaping bar secured in position on a shaping arm;

FIG. 3 is an end elevation of the shaping press in operation with the supporting mandrel and preformed blade blank in section;

FIG. 4 is a side elevation of the apparatus of FIG. 3 on a slightly reduced scale;

FIGS. 5-7 are fragmentary sections showing the cooperation between the shaping bars and the supporting mandrel as a blank blade is folded;

FIG. 8 is a cross section through a folded blank showing the trailing edges in close proximity for joining; and

FIG. 9 is a sectional fragmentary perspective showing a completed blade shape.

Referring to the drawings which illustrate a preferred embodiment of the invention, a first or lower mounting plate 10 has a pair of supporting standards 11 extending from two corners thereof and a pair of elongated mandrel supports 12 which are attached to mounting plate 10 by nuts 13 and bolts 14. A supporting mandrel 15 is removably attached to mounting plate 10 and supports 12 by means of set screws 16 which extend through the supports 12 into the base portion of the mandrel.

The supporting portion 17 of mandrel 15 is constructed into a shape corresponding substantially to the cross sectional shape of a completed compressor or turbine blade in order that the precisely formed contours of the blank 18 can be preserved during the folding operation. The blank 18 includes a leading edge 19, a nose portion 20, which constitutes that portion of the blank immediately adjacent each side of leading edge 19, and trailing edges 21. Trailing edges 21, best shown in FIG. 8, are located at the point where the folded sides make contact at the dished portion of the sides just ahead of the excess portions 22, the portions 22 being removed in subsequent operations. An abutment 23 is formed at each end of the shaping mandrel to provide for accurately positioning 'a blade blank 18 on the mandrel prior to the folding operation. The upper surfaces 24 of the abutments 23 control the downward travel of the shaping bars as shown in sequence in FIGS. 5-7.

A second or upper mounting plate 25 is attached to standards 11 by means of apertured ears 26, which extend outwardly from two corners of the mounting plate 25, to provide a plate for movement in opposition to the first plate 10. Holding means 27 is attached to that surface of mounting plate 25 which faces the lower mounting plate so that shaping arms 30 can be mounted for cooperation with the mandrel 15. The holding means 27 includes a pair of generally parallel arms 31 having inwardly directed hinge plates 32 which are spaced to cooperate with extensions 35 on the shaping arms 30 so that hinge pins 36 can be placed within the axially aligned holes 37. Holes 37 extend through hinge plates 32 and extensions 35 to provide for pivotal attachment of the arms 30 to holding means 27.

The inner end of each shaping arm 30 has a cut-out portion 40 for receiving an elongated shaping bar 41, the shaping bar being removably secured to its shaping arm 30 by means of screws 42 and retaining plates 43 which are held in position by screws 44. The adjoining inner ends of shaping arms 30 are close enough together that the upper corners will almost touch when the arms are resting in their lowermost position, as shown in FIG. 5 of the drawings. It should be noted that retaining bolts 45, having washers 46, extend through openings 47 in arms 30 for threaded engagement with holding means 27 to provide a positive limit on the downward travel of the arms 30.

It is normally preferred that upward movement of arms 30 present some resistance to the mandrels so that the blade blank 18 will be urged tightly against the mandrel. This is accomplished by a plurality of coil springs 50 which bias the spacing arms 30 toward their lowermost position so that the shaping bars 41 will form a generally V-shaped notch 51 for receiving the upper edge of mandrel 15 together with the blade blank.

In the operation of the shaping apparatus the upper mounting plate 25 and lower mounting plate 10 are placed in a press for relative movement toward each other and preformed sheet metal blade blank 18 is positioned on mandrel 15 so that its nose portion 20 and leading edge 19 will be supported by the upper edge of the mandrel. FIGS. 5 through 7 indicate the manner in which the blade blank is subjected to a folding force resulting from the toggle-like action of the opposed, cooperating shaping hars 41 on shaping arms 30. As the upper shaping means is lowered to make contact with mandrel 15, or vice versa, the nose portion of the blade and the supporting mandrel move into notch 51, contact being initially made with shaping bars 41 immediately adjacent each side of leading edge 19 of the nose portion 20. As the movement is continued the shaping arms begin to swing upwardly and exert substantial lateral or side forces against the nose portion of blade blank 15 and consequently bend the blank about leading edge 19.

The vertical force, i.e. that which acts against the blank in the same general direction as a blade chord, is comparatively light since the bars 41 continually retreat against the biasing force of springs 50 as the blade is forced further into notch 51. Since the notch 51 closes during the pivotal movement of arms 30 the blade is subjected to transversely acting forces beginning adjacent each side of the leading edge 19 and continuing therefrom toward the trailing edges 21 to fold the blade blank about its leading edge. Since the cross sectional sectional area of a completed blade the blade can be folded far enough to insure that it will achieve the proper shape without the necessity of further forming operations.

The present invention is of particular utility in those cases where the nose radii of the complete blade is extremely small, for example on the order of the thickness of the blade wall. The use of high vertical forces in folding the blade blanks about the mandrel would cause failure of the mandrel after a relatively few folding operations. However where the folding operation is largely accomplished by large side or transversely directed forces close to the leading edge of the blank and there is limited pressing or dragging by friction of the blank vertically downward against this edge, the mandrel will withstand thousands of folding operations. This is particularly true in this invention since the large side forces tend to rework and reform the mandrel while it is within the nose of the blade blank eliminating distortions of the mandrels edge which may have occurred accidentally or through the operation with an incorrect blade blank.

The edge of the mandrel 15 is also protected against large vertical forces by the retaining plates 43 which strike abutments 24 at each end of the mandrel when the mandrel and the shaping arms 30 are being moved relatively together. Thus the upward pivotal movement of the shaping bars is completed by reason of the plates 43 coming into contact with abutments 24. Plates 43 may be of varied thicknesses to achieve different degrees of vertical and side forces, the amount of each of the forces used depending upon the shape and the size of mandrel present. With proper selection of plate thicknesses the vertical forces can be of slight magnitude while preserving relatively greater side forces to achieve proper folding of a blade blank about the mandrel. It will thus be clear that the main folding action of the shaping arms results from the contact of the plates 43 with the abutments 24 and not from the opposition of the edge of the mandrel.

The present apparatus is also useful in reforming the upper edges of a mandrel which have become deformed from long use. By exerting the large transversely directed forces against the nose portion of the mandrel, it can be shaped by the roller-like action of the toggle construction to reform it into proper configuration. The operation is analogous to that described in connection with the folding of the blade blanks.

While the form of apparatus and method herein described constitutes preferred embodiments of the invention, it is to be understood that this invention is not limited to these precise forms of apparatus and method and that changes may be made therein without departing from the scope of the invention which is defined in the appended claims.

What is claimed is:

1. An apparatus for folding an open, preformed contoured blade blank about the leading edge of its nose portion to bring the trailing edges into close proximity for joining while preserving the preformed contours over the major portion of both blade surfaces, said apparatus comprising a fixed mandrel conforming to the configuration of and receiving thereon the nose portion of said blade blank to provide support therefore, blade nose shaping means mounted in opposition to said blade blank, and means for applying force directly to said shaping means to exert "a transversely acting force against the nose portion only of said blade blank beginning adjacent each side of the leading edge and continuing therefrom over the forward portion of said blank to fold said blade blank about its leading edge leaving the major portions of said blank rearward of said forward portion with said preformed contours therein.

2. An apparatus for folding an open, preformed contoured blade blank about the leading edge of its nose portion to bring the trailing edges into close proximity for joining, said apparatus comprising a first mounting plate, a mandrel having a shape conforming substantially to the shape of a completed blade up to the trailing edge thereof secured to said mounting plate and providing support for said blade blank, a second mounting plate supported in opposition to said first mounting plate, shaping means attached to said second mounting plate, said shaping means including a pair of pivotally mounted cooperating shaping bars arranged for contact with the nose portion only of said blank adjacent each side of the leading edge thereof, and means responsive to the relative movement of said plates for operating said shaping means independently of the engagement of said nose portion therewith to limit the chordwise force on said mandrel and to exert transversely acting forces on said blade blank which fold said blank about its leading edge leaving the major portion of said blank with said preformed contours therein.

3. Apparatus for working an open, preformed contoured blade blank to form a folded blade with nose radii in the order of thickness of the blade wall and to bring the trailing edges into close proximity for joining, comprising a press including a first mounting plate thereon, a mandrel having a relatively sharp leading edge secured to said first mounting plate providing support for said blade blank, a second mounting plate supported on said press for relative movement with said first plate, a pair of opposite shaping bars pivotally attached to said second mounting plate for closing movement in pressure contact with the nose portion of said blank adjacent each side of the leading edge for exerting transverse forces on said blank to fold said blank about the leading edge thereof, and an abutment forming an integral extension of said mandrel engageable with said bars to complete said closing movement thereof upon relative movement of said plates, said bars and abutment being pro portioned to limit said relative movement for protecting said mandrel against excess pressures normal to the leading edge thereof.

4. Apparatus for working an open, preformed contoured blade blank to form a folded blade with nose radii in the order of thickness of the blade wall and to bring the trailing edges into close proximity for joining, comprising a press including a first mounting plate thereon, a mandrel ahving a relatively sharp leading edge and having a cross sectional area less than the internal cross sectional area of such completed blade, said mandrel being secured to said first mounting plate providing support for said blade blank, 2. second mounting plate supported on said press for relative movement with said first plate, a pair of opposite shaping arms pivotally attached to said second plate, a shaping bar secured to each of said shaping arms for movement with said arms to a closed position in pressure contact with the nose portion of said blank adjacent each side of the leading edge for exerting transverse forces on said blank to fold said blank about the leading edge thereof into conformity with said mandrel leading edge, and a pair of abutments forming integral extension of said mandrel positioned at each end thereof engageable with said arms to complete closing movement thereof upon relative movement of said plates and said abutments and arms being proportioned to limit said relative movement for protecting said mandrel against excess pressures normal to the leading edge thereof.

5. Apparatus for working an open, preformed contoured blade blank to form a folded blade with nose radii in the order of thickness. of the blade wall and to bring the trailing edges into close proximity for joining, comprising a press including a first mounting plate thereon, "a mandrel having a leading edge conforming substantially to the internal configuration of the leading edge of a completed blade and having a cross sectional area less than the internal cross sectional area of such completed blade, said mandrel being secured to said first mounting plate providing support for said blade blank, a second mounting plate supported on said press for relative movement with said first plate, holding means having hinge plates extending from a surface thereof attached to said second mounting plate, a pair of opposite shaping arms attached to the hinge plates of said holding means, a shaping bar secured to each of said shaping arms for movement with said arms to a closed position in pressure contact with the nose portion of said blank adjacent each side of the leading edge for exerting transverse forces on said blank to fold said blank about the leading edge thereof into conformity with said mandrel leading edge, plates removably cartried on each end of said arms adjacent said bars, and a pair of abutments formed on extended portions of said mandrel engageable with said arms at said plates to complete closing movement thereof upon relative movement of said plates, said abutments and plates being proportioned to limit said relative movement for protecting said mandrel against excess pressures normal to the leading edge thereof.

6. The method of completing the folding of an open, partially folded preformed contoured sheet metal blade blank about the leading edge of its nose portion to form the completed blade shape characterized by a nose radii in the order of the thickness of the blade Wall compris ing, supporting the partially folded blade blank on a mandrel having a supporting leading edge surface conforming to the desired internal configuration of the completed blade nose portion, exerting a vertically directed force on the nose portion only of the blade blank to urge the nose portion into firm engagement with the mandrel, and simultaneously applying transversely directed forces directly to the blade blank while limiting said vertically directed force to fold the blade about its leading edge in conformity With said mandrel and bring the trailing edges into close proximity for joining, said transversely acting forces being progressively applied to said nose portion beginning adjacent each side of the leading edge and moving therefrom over the forward portion only of said blank leaving the major chordwise extent thereof unworked and with its original contours therein.

References Cited in the file of this patent UNITED STATES PATENTS 395,723 Vanstone Ian. 8, 1889 1,003,197 Ohl Sept. 12, 1911 1,207,624 Rehbein Dec. 5, 1916 1,771,681 Kahn July 29, 1930 2,286,255 Brooks June 16, 1942 2,373,163 Cailloux et al Apr. 10, 1945 2,373,822 Geppelt Apr. 17, 1945 2,418,100 Stewart Mar. 25, 1947 2,433,841 Glud Jan. 6, 1948 2,443,596 Cahill June 22, 1948 2,473,533 Lebedefr' June 21, 1949 2,485,495 Kenney et al. Oct. 18, 1949 2,522,683 Lurcott Sept. 19, 1950 2,604,136 Nase July 22, 1952 2,675,608 Vines et al. Apr. 20, 1954 FOREIGN PATENTS 651,117 Great Britain Mar. 14, 1951

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